Electric heating unit



Oct. 27, 1925.

A. D. KEENE ELECTRIC HEATING UNIT Filed Dec.. 13. 1923 liiillll BBB WITNESSES ATTORNEY Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

ALVIN D. KEENE, or PITTSBURGH, rnNNsYLVANIA, 'AssIGNoa 'ro wE's'rINeHoUsn ELEcrRIc a MANUFACTURING coMrANY, A coBroaATIoN or PENNSYLVANIA.

ELEcrraIc HEATING UNIT. i

Application med December 13,1928. Serial No. 680,393.

To all whom #may cio/miem.'v I v "Be it known that I, ALVIN l). KEENE, a citizen of the United States, and a resident of Pittsburgh, inthe county of Allegheny 5 and State of Pennsylvania, have invented' a new and useful Improvement in Electric Heating Units, of which the following is a specification.

My invention relates to electric heating devices and particularly to heating units for electric lresistance furnaces..

The object of my invention is to provide a relatively simple and compact structure for a quickly removable and self-contained heating unit of relatively highcapac'ity, that shall have both ends of the resistor element located at one endof the unit.

` -In practicing my invention, I provide a relatively heavy resistor wire that lis wound in the form of a flat helix of (double pitch, the adjacent turns of which are spacedfrom each other. Refractory members, of electric-insulating material, each having a plurality of spaced pockets in one face thereof,` operatively' engage the end portions only of` each turn.

A metal frame having side portions of overhanging channel section interft with the refractory members to hold them in their proper operative positions, metal end pieces eing providedto complete the metal frame and provide a substantially unitary structure. The two ends of the resistor member the end-pieces of the metal frame.

' In the drawings, Y

Figure 1 is a View, in vertical longitudinal section, through an electric furnace comprising the device embodying my invention,

Fig. 2 is a view, partially in side elevation and partially in longitudinal vertical section, of an electric heating unit embodying my invention, and Y Y Fig. 3 is a view in vertical lateral section therethrough taken on the lineeIII-III of Fig. 2.

An electric resistance furnace 11 comprises a plurality of outer side and end WallsV 12, a bottom wall 13 and a to wall 14, each made of suitable refractory eat-insulating bricks or blocks. An inner lining 15 is provided for each of the outside Walls and may extend through suitablebushings in one ofl comprise avplurality of bricks or blocks of a suitable high-temperature resisting refractory material usually employed in the art.

The walls are so spaced apart as to provide a furnace chamber 16, of any suitable or desired contour and dimensions. I have shown a particular furnace structure 4for illustrative purposes only in order to show more particularly the application of and the location in, such a furnace structure of aheating unit embodying my invention and to V .be hereinafter described in detail. I

A heatingunit 17 comprises a relatively heavy resistor member 18 in the form of awire or rod that is preformed to the shape of a flat helix, as is illustrated more par'- ticularly in Fig. 3 of the drawin The he- .length and then winding the same with .a

uniform spacing between the adjacent vturns of the helix. The distance between adjacent 3 of the helix, as well as in accordance with the object of having as much as possible of the heat radiating surface of the resistor vturns of the helix is in accordance with the i dimensions of the wire and the dimensions memberso located that the heat generated thereby or therein will have a free and unobstructed .sister mem r Kto material, to be heated thereby! and located adjacent thereto.

A plurality of refractory supporting 'and high temperature resisting material, are provided, and each has a plurality of spaced ockets 21 in the inner face thereof into which the rounded end portions 'of each turn of the resistor member 18 may fit. The distance between the adjacent turns of the resistor member 18 should be at leastsufciently large to make the walls between the adjacent pockets 21 suciently ath from the surface of the remembers 19 of a suitable electric-insulating I heavy to resist `such strains as ma be placed` thereon during the assembly an disassembly of the heating units and during the operation thereof.

A metal frame for the vrefractory members 19, a lurality of which may be located in en -to-end relation at each side of the flat helix comprises a pair of metall side members 22, of channel form 1n lateral section. The overhanging flanges of the side members 22 cooperate with the refractory members 19 to interit therewith and to prevent lany movement of the refractory members laterally of their length. A shoulder portion 23 is provided at each side of the members 19 to permit of this interfitting relation.

End members 24, of a suitable length,

are provided and are secured to the side members 22 by aplurality of bolts 25. As the' temperatureof the heating uit is relatively high, it is desirable thatl all of theV s metal portions of the frame be made of a substantially non-oxidizable vmaterial, vand I prefer to employ .the material called nichrome for this purpose.

One of the end members 24 is provided with a plurality of spaced openings 26 therethrough in which are located bushingsY 27 of refractory electric-insulating material having an opening therethrough, through which the ends ofthe resistor member 18 may eXtend,-as shown more particularly in Fig. 2 ofthe drawing.

The bushings 27 are provided with a radialliange at one end and a s ring clamping ring 28 located in a perip eral groove adjacent to the other end to hold the bushings in their proper operative position with- 'in the openings 26 during the operation of the heatinglunit.

` In assembling the *heating unit, the two side members 22 and one end member'24 maybebolted together and laid in their proper operative positions on a suitable supporting surface after which the members` 19 may be moved into their positions longitudinally of the side members 22 from the' open end of the. unit. The resistor member A18 may be placed in its proper operative positions` relatively vto the refractory members 19, before the latter are moved into their proper operative positions, and it is only necessary then to place in position the end member 24 having the bushings 27 therein and then bolt the end members as hereinbefore described.

\ Another method of assembly that may be employed is to place the refractory memtrated several method according to which I may assemble a plurality of heating units of the hereinbefore described type, closely substantially overhung adjacent to the side or the end walls of a furnace structure. `For instance, I may mount a plurality of heating elements 17 in superposed relation, as is illustrated more.'

particularly in the right hand part of Fig. 1 of the drawing,'it being understood, of course, that the width or height ofl each heating unit is such that substantially all of the surface of the side wall may be covered l with-heating units.

Instead of bolting the side and end mem- I haveillustrated another method of mounting theheating unit embodying my invention-in a furnace structure, in which case, the individual heating units -rest upon 4an end surface thereof, which is., of course, the one opposite4 to that end having the ends of the resistor member projecting therefrom.

As the resistor rod or wire' is relatively heavy, it is possible to place the individual heating units in either of these positions, as well as in a substantially horizontal or lat position above or below a heating chamber, without appreciable deformation of the straight portions of the resistor member.

Any suitable or desired means may be employed to hold the individual or assembled plurality of heating units in their proper operative positions within the furnace structure and lI have indicated two methods in Fig. 1 of the drawing. I may provide grooves 29 in the inner surface of the lining 15, substantially as indicated in the Vright hand portion of Fig. 1 of the drawing, into which the individual or'assembled heating units may be placed, either by a movement longitudinally of the groove 29 or if the depth of the upper groove 29 is made greater than that of the other or lower'groove 29, the assembled-heating units may be placed in their proper operative positions by a lateral or tilting movement thereof, the upper end of "the heating unit being' placed in the deeper groove 29 and thenl moved upwardly until the lower end clears either the refractory lining adjacent to the groove 29 or until 1t clears the upper edge of a heating unit 17 already installed.

Another means of holding the individual or assembled heating units, may comprise i metal rods 31 built into the furnace strucbers ofeach heating unit, I may employ ture and. key members 32, of substantially `metal frame of the heating units. This construction is illustrated more particularly in the left-hand portions of Fig. 1 of the filed July 6, 1923, and assigned tothe Westinghouse Electric- & Mfg. Co.

The end portions of the resistor member that are connected to the ends of` suitable supply circuit conductors (not shown) fare `preferably bent at right angles to the plane of the individual'` heating unit in order that the heating' units may be installed by a movement substantially at rlght angles to Y the plane thereof an'dthese end portion .may

extend throuy h suitable bushings 33 provided in the fgurnace structure.l

The bushings 33 may'be of anysuitable or desired construct-ion and, as they form no part of my invention, they are not further described nor illustrated.

The device embodying my invention thus provides a heatingunit thatmay be placed and supported in a plurality of operative positions, such as on edge at eitlier sid e or at one end thereof, or flat upon a suitable skeleton supporting frame, and in which frame 'both ends of the resistor` wire are located at one end 'of the heating unit, whereby -easy and quick connection of operatively assembled heating unitsmay be effected. Y

Va'rious modications and changes may be made without departing from the spirit and scope of the invention, I desire, therefore, that only such limitations shall be placed therein, as are imposed by the prior art.

-I claim as my invention:

1. In an electric heating unit, the com.

bination with a metal frame, and a plurality of refractory members supported thereby and having a plurality of spaced pockets in one surface thereof, of a resistor member Wound in a double pitch ilat helix extending between spaced refractory members and having the roundedend portions-located inksai pockets.

2. In an electric heating unit, the comi bination with a metal frame having two side members of substantially overhanging channelsection and a plurality of refractory members located in and supported by said side members and each having a plurality of spaced pockets in the outer face thereof, of a resistor member wound in the form of a double pitch flat helix extending between spaced refractory members and having'the rounded-end portions located in said pockets.

3.'In an electric heating unit, the combination with a metal frame, and a lplurality of refractory members supported thereby and having a plurality of spaced pockets in one surface thereof, of a resistor member wound in a double pitch flat helix extending between spaced refractory members and having the rounded end portions located in said pockets, and a plurality of spaced refractory thimbles supported by said frame at one end thereof for receiving and supporting the ends of-said resistor member. `In testimony `whereof, I have hereunto subscribed'my name this 28th day of November, 1923. l

ALVIN D. KEENE. 

